American Idol winner Kelly Clarkson is officially off the market.

The season-one champion took to Twitter to make the announcement to her fans, tweeting: "I'M ENGAGED!!!!! I wanted y'all to know!! Happiest night of my life last night! I am so lucky and am with the greatest man ever "

The "greatest man ever" is her boyfriend, Brandon Blackstock, Reba McEntire'sstepson. The pair, who have known each other for years, reconnected in February at the Super Bowl, where Clarkson sang the national anthem.

Clarkson has been walking on air this year over the romance, telling People how her new relationship has affected her songwriting while promoting her summer show on NBC, Duets.

"I'm trying to write a tough song, and it is coming out like butterflies and rainbows," she said.

Clarkson will share the stage with American Idolseason-eight finalist Adam Lambert tomorrow for the VH1 Divas concert honoring Donna Summerand Whitney Houston, who both died in 2012.

"Unfortunately, we're not gonna be singing together, but we'll be on the same bill," Lambert tells The Hollywood Reporter. "I've met her, and she's lovely and so down to earth, and her voice is amazing. She can sing anything. She was doing a lot of covers on her tour, and I've seen a lot of them online. There's nothing she cannot sing."

For those curious about the ring, Clarkson offered more details on her Twitter account Saturday afternoon: "It's a yellow canary diamond with diamonds around it and Brandon designed it with Johnathon Arndt! They did an amazing job!